The effectiveness of antivenom in countering the actions of box-jellyfish (Chironex fleckeri) nematocyst toxins in mice.

The neutralizing ability of commercially available antivenom prepared against 'milked' box-jellyfish (Chironex fleckeri) venom was tested intravenously in mice against crude nematocyst venom obtained by crushing isolated nematocysts and against each of two lethal toxins (T1 and T2) present in this venom. The in vitro neutralizing ability of the antivenom against crude venom was reduced markedly compared with its reported neutralizing ability against 'milked' venom whilst the in vivo neutralizing ability of the antivenom tested in both prophylactic and rescue experiments involving crude nematocyst venom was reduced approximately threefold. When tested in vitro and prophylactically in vivo the neutralizing ability of the antivenom was much more pronounced against T2 than against T1. This finding was in accord with the view that T1 was absent from the 'milked' venom against which the antivenom was prepared. Doses of crude venom in excess of twice the lethal dose killed mice within 2-3 min emphasizing the need for speed in the administration of antivenom.